Like ssulivan, I have noticed a number of cored hulls with "issues". No problem if its noticeable, one simply moves on. The worrying thing is if it surveys o.k. and then after a year or two it begins to fall apart.

Curious that amongst all the posts regarding the esoterica of the various resin properties, no mention of the expected life span of the total structure is mentioned.

Of course, no material is forever but most are economically feasible to repair and refurbish. Is the cored structure among those.?

I think this is a very important statement, Neelie. I don't want to put a lot of drift into Bit Cat's thread covering construction, but I'll say one last thing on it in this thread:

We have entered this era. There are many boats out there on the used market from the time period you are talking about that are falling apart already, while well built boats from the 60's and 70's are going strong still.

As with most products you buy during these times of lower quality, boats seem to have slipped too (some boats - of course others have been built to a different standard, but your average person can't afford those new).

I'd say you can make a direct comparison between boat build quality and say.... anchor shackle build quality. Take a close look at those "China" West Marineanchor shackles, then look at a shackle from the mid-80's if you can find one on a boat. I feel that many boats have gone this way as well.

I cringe every time I see a new production boat that someone paid big bucks for. I look closely at it and note how all the hardware gets smaller and smaller and smaller. How the hull can be deflected so easily, how they are built to look good rather than to last.

To me, a boat is a lifetime purchase, not something you replace after a few years cruising. If the boat doesn't last my whole life, it's garbage. Many of the boats made 10 years ago (and probably more so today) are showing signs of falling apart in ways the older boats don't (cored or not).

That's why this time, I went with build strength and solid glass over performance. I completely ignored age, condition and if I "loved" the boat or not. I went with pure, cold logic and ended up with a battleship. May not win the races, but I can sleep easy knowing it's going to last.

Sean, while I too own an older British cat that is (over?)built like the proverbial brick sh*thouse (and for many of the same reasons that you espouse), I am not about to equate 'heavy' with longevity. There has been a huge advance in design technology (computer analysis of stress etc.), materials and building technology that permit very strong and yet incredibly light boats. In a sense, you can get the best of both worlds - IF you are prepared (or able) to pay for it.

Cored hulls have been around for a long time and many have held up very well, even though the early ones were constructed without resin infusion technology. The Niagara 35, for example, was built in the late 70's/early 80's with a cored hull and I have never heard of delamination problems on the hull itself (the deck was another matter). The key was care during construction and keeping solid laminates below the waterline ( or at least ensuring that there is solid glass where any thru-hull etc. was going to be installed).

I am sure that you have read many of Gideon's posts, and while his boats are incredibly light weight, you can sense the effort and care that has gone into the engineering in order to ensure solidity and durability. My only real knock on properly engineered/constructed cored hulls is the relative difficulty in repairing the same if one suffers some collision damage. On the other hand, since weight is the enemy of performance in catamarans, they are particularly well suited to high-tech composite construction.

Sean, I didn't take it that you were attacking anyone's boats. Like you, I found the solid construction of an older British cat to be a huge positive. Also, like you, my boat is ultimately going to be used to take people out on day-charters and the less-aerodynamic coach house provides additional seating, and the full bow pulpit additional security for non-sailors. I must say, though, that in the future (once I am through with guests, or can afford two boats) I would still like a high performance cruising cat for my own purposes. Inevitably that is going to mean composite construction in the hulls.

Yes, there is a lot to be said about solid glass hulls. On older boats, there is much less chance of serious structural issues and, as already alluded to, they are much easier to repair in the case of damage. But that does come at the expense of performance and, watching videos of Outremers and Gunboats screaming along at over 20 knots has whet this sailor's appetite....

BigCat, where are you building your catamaran? Isn't real estate for that size boat in Seattle rather expensive? I noticed the USCG reference; are you building it for commercialcharter operations? If so, you have my sympathy when dealing with USCG and cat design!

Hi, Evan

I am about 35 miles north of Seattle in the country, but just barely in the country-cattle, horses, sheep, etc. surround me, but just a mile away is a freeway entrance, several grocery stores, banks, gas stations, a Costco, etc. I have a 5 acre property with a house, a 3200 square foot shop, and now a semicircular tent 70 feet long and 35' wide. Just 4 miles away is a Composites One branch and a Meridian Yachts factory, so all in all, it is pretty convenient but not too expensive.

The boat is a dual purpose job, with yacht accommodations but passenger-carrying approval. The Coast Guard is actually used to cats now. They have a formula for sailing cats' rig size, but it would have allowed me more sail area than I wanted-I have 2400 sq. ft. on a 65' boat. To call the USCG requirements stringent is an understatement. Getting the plans approved (which I am told is about to happen,) has taken me 9 months and maybe a thousand man hours. I am told that I may expect weekly visits by a USCG inspector once I actually commence building-

Whoops! I had misread your post, so of course I see you are replying to my delete thread.

Sorry for any confusion.

Quote:

Originally Posted by Southern Star

Sean, I didn't take it that you were attacking anyone's boats. Like you, I found the solid construction of an older British cat to be a huge positive. Also, like you, my boat is ultimately going to be used to take people out on day-charters and the less-aerodynamic coach house provides additional seating, and the full bow pulpit additional security for non-sailors. I must say, though, that in the future (once I am through with guests, or can afford two boats) I would still like a high performance cruising cat for my own purposes. Inevitably that is going to mean composite construction in the hulls.

Yes, there is a lot to be said about solid glass hulls. On older boats, there is much less chance of serious structural issues and, as already alluded to, they are much easier to repair in the case of damage. But that does come at the expense of performance and, watching videos of Outremers and Gunboats screaming along at over 20 knots has whet this sailor's appetite....

"...because it is end grain and drinks it in." The major balsa suppliers supply pre-coated balsa that does not 'drink it in.' I agree that if you are coring with, say, cedar, you should use epoxy, but it is simply an error in logic to assume that all 'timber' has the same properties. Your posts subsequent to my last reply to you still completely lack documentation to support your claims. There is another thread, 'balsa', where a lot of this has been recently discussed in detail.

Brad, I was listening to the online seminar a couple of days ago on composite construction, and a composites engineer claimed that it was no more difficult to repair core than solid laminates. I don't see why it should be all that difficult to repair core laminates, and I have done a fair amount of hand laminating. If the damaged area were fairly small, I would just make a solid repair.

Dave, repairs are not always done in epoxy, and Derek Kelsall will be happy to supply kits for catamarans made with polyester / foam or vinylester / foam. I have already posted a link to a boatyard that has done repairs exclusively with vinylester for the last 8 years. As usual, you are long on opinions and 100% fact free.

I don't mind if you or anyone else wants to build in epoxy, but I won't let you or anyone else get away with slandering the alternative unopposed-obtainable as very fire retardant, much less toxic, at least 97% as strong, and less expensive alternative- VE, aka Vinyl Ester, aka Vinylester.

I am about 35 miles north of Seattle in the country, but just barely in the country-cattle, horses, sheep, etc. surround me, but just a mile away is a freeway entrance, several grocery stores, banks, gas stations, a Costco, etc. I have a 5 acre property with a house, a 3200 square foot shop, and now a semicircular tent 70 feet long and 35' wide. Just 4 miles away is a Composites One branch and a Meridian Yachts factory, so all in all, it is pretty convenient but not too expensive.

The boat is a dual purpose job, with yacht accommodations but passenger-carrying approval. The Coast Guard is actually used to cats now. They have a formula for sailing cats' rig size, but it would have allowed me more sail area than I wanted-I have 2400 sq. ft. on a 65' boat. To call the USCG requirements stringent is an understatement. Getting the plans approved (which I am told is about to happen,) has taken me 9 months and maybe a thousand man hours. I am told that I may expect weekly visits by a USCG inspector once I actually commence building-

Welcome to the fun world of dealing with the Coasties and passenger for hire vessels where the only thing consistent are the inconsistencies. Get used to the never ending inspections where they will keep finding things that need correcting, you correct them and when they come back to inspect your corrections, they find even more things that need correcting...and so forth and so on. Perhaps if they were a little easier, we might actually have a merchant marine that is larger than that of Somalia's merchant marine! But no, its their job to keep people absolutely safe even if it regulates all of the US merchant ships out of existence.

Hi, Dave M-This is a sub-T boat, and I have practically memorized CFR 46. This boat is to be licensed to carry 149 passengers-you increase the pain exponentially as you go from 6 to 49 to 149 to more passengers. My pain tolerance maxed out at 149 passengers / under 65'.

Dave, repairs are not always done in epoxy, and Derek Kelsall will be happy to supply kits for catamarans made with polyester / foam or vinylester / foam. I have already posted a link to a boatyard that has done repairs exclusively with vinylester for the last 8 years. As usual, you are long on opinions and 100% fact free.

.

I see, What about balsa?

My facts come from experience in the real world, not the internet, but as stated previously, many have and do use poly and Balsa, just dont expect me to believe its better than epoxy balsa